Before the Easter Weekend, I was lamenting my problem using an external co2
reactor on the intake side of a canister filter. Scott Hieber had kindly
replied, "What model Eheim are you using? What's the media in the filter?"

In my 20L, I have an Eheim Ecco 2231 (rated for up to 35g tanks/127gph with
standard Ecco coarse pad/sintered glass/fine pad) that wasn't able to keep
up?the flow was a sad trickle by the end of the reactor body. I even tried
shortening the reactor from 12? to about 6". I tried this on the outflow
side with similar results. Here are two thumbnail pics:

In the July-Sept ?04 issue of the AGA journal, Ghazanfar Ghori wrote about
excellent results with an external reactor on the intake side of his Eheim
2026 (up to 92g tanks/172 gph) on his 75g tank.

Reggie Bustinza from this forum has a beautiful 29g tank with a very
effective external reactor on the OUT-flow side using an Eheim Pro 2224 (up
to 75g tanks/185 GPH).

This gph difference between the three setups above and their tank size has
me confused why my results are so different. Fuzzy mathmatics?

I want to use this method instead of my internal reactor because the noise
from my Rio90 is too loud in my shoebox-sized apartment. And because I'm
intrigued by the dissolution Ghazanfar describes and results which I've seen
in Reggie?s tank.

I don't mind paying for another canister (I will use the old one on another
tank) but have an AWFUL record of bad luck when I think I've ?purchased a
solution" to a problem. Based on the examples above, what would be the best
specs for my setup? I know I could buy the biggest filter out there, but
hoped you folks could make some recommendations?or please, let me know if I
missed the point somewhere as usual :-)